There are two methods of cache-coherency which are as follows −Cache–Memory CoherenceIn a single cache system, coherence between memory and the cache is maintained using one of two policies − (1) write-through, and (2) write-back. When a task running on a processor P requests the data in memory location X, ... Read More

A shared memory model is one in which processors connects by reading and writing locations in a shared memory that is similarly applicable by all processors. Each processor can have registers, buffers, caches, and local memory banks as more memory resources. Some basic issues in the design of shared-memory systems ... Read More

The character-oriented protocol is depends the binary code of a character set. The code generally used is ASCII (American Standard Code for Information Interchange). It is a 7-bit code with an eighth bit used for parity. The code has 128 characters, of which 95 are graphic characters and 33 are ... Read More

The Intel 8089 l/0 processor is contained in a 40-pin integrated circuit package. Within the 8089 are two independent units called channels. Each channel combines the general characteristics of a processor unit with those of a direct memory access controller.The 8089 is designed to function as an IOP in a ... Read More

The I/O processor in the IBM 370 computer is known as a channel. A general computer system configuration contains multiple channels with each channel connected to one or more I/O devices.There are three types of channels including a multiplexer, selector, and block-multiplexer. The multiplexer channel can be linked to multiple ... Read More

The daisy-chaining method of creating priority includes a serial connection of all devices that request an interrupt. The device with the highest priority is located in the first position, followed by lower-priority devices up to the device with the lowest priority, which is situated last in the chain. This technique ... Read More

The transfer of data between two units can be finished in parallel or serial. In parallel data transmission, each bit of the message has its direction, and the complete message is sent at a similar time. This defines that an n-bit message should be sent through n separate conductor paths.In ... Read More

The strobe control technique of asynchronous data transfer operates a single control line to time each transfer. The strobe can be activated by either the source or the destination unit. The diagram shows a source-initiated transfer.The data bus gives the binary data from the source unit to the destination unit. ... Read More

In this transmission, signals are sent between the computers and external systems or vice versa asynchronously. This generally defines data that is sent at infrequent intervals instead of in a steady stream, which represents that the first element of the execute file might not ever be the first to be ... Read More

Isolated I/OIn the isolated I/O configurations, the CPU has definite input and output instructions, and each of these instructions is related to the address of an interface register. When the CPU fetches and decodes the operation code of an input or output instruction, it locates the address related to the ... Read More